UNIQUE MORPHOLOGICAL INNOVATION AND POPULATION VARIATION IN GAMMATRICULA-SONGI, A NEW SPECIES OF TRICULINAE FROM CHINA (GASTROPODA, RISSOACEA)

A new species, Gammatricula songi Davis and Chen, is described from Zh ejiang Province, P.R. China. This species is unique due to remarkable innovations of the female reproductive system, especially an enormous accessory bursa copulatrix that upon first examination appears to be t he pallial oviduct. The species is widely distributed in Kai Hua Count y of western Zhejiang Province. It is possible for the first time, to analyze intra and inter-population variation in a triculine species us ing suites of quantitative data. Multivariate analytic procedures were used to demonstrate subtle but significant differences among some pop ulations. This study shows conclusively that the suites of quantitativ e anatomical characters (measurements of organs) are useful to show in terpopulation divergence. On the whole, a single population has 57% or more of species-wide variation. Cladistic analyses show the species t o belong to the Triculinae: Pachydrobiini. It is a derived taxon in a trichotomy with Gammatricula chinensis and Wuconchona niuzhuangensis. A new genus is not raised for G. songi pending further investigations that clarify the bounds of the genus Gammatricula.